Banca de QUALIFICAÇÃO: WILLIAM DANIEL ALVES BEZERRA DA SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : WILLIAM DANIEL ALVES BEZERRA DA SILVA
DATE: 29/01/2024
TIME: 09:00
LOCAL: Ambiente virtural Google Meet
TITLE:

INVESTIGATION BY COMPUTATIONAL MODELING OF CATALYZED ALLYATION REACTIONS

KEY WORDS:

Cobalt, Allylation Reaction, DFT, Gibbs Free Energy.

PAGES: 159
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Química Teórica
SUMMARY:

In recent decades, there has been a strong push to try to replace precious metals with catalysts that are more economical, abundant and efficient, to promote more sustainable chemical synthesis. The use of metals such as cobalt has become attractive as an efficient and more economical catalyst in the synthesis of new materials. Furthermore, there is evidence that Co (II) salts as catalysts are effective for the allylation reaction. Additionally, such reactions can be carried out using organic trifluoroborate salts, which are more stable than the commonly used lithium and magnesium salts, can promote chemoselective processes, and can be carried out in water. Recently, a research group from the Federal University of Campina Grande, led by prof. J. C. R. de Freitas has been developing experimental research with allylation reactions catalyzed by cobalt salts, such as CoCl₂, in aqueous/biphasic media. Preliminary results show that such a system is efficient for substrate conversion and even show chemoselectivity of the catalyst, with preference for reactions with aldehyde-type substrates in relation to ketones. Due to the scarcity of experimental and modeling data that explain the mechanism of allylation reactions involving Co, different complexes that may be active species in mechanisms involving allylation reactions catalyzed by Co were investigated in this work. Co complexes coordinated to methanal, propanone and allyl compound, in structures with only water ligands or also with chloride ligands in different isomerisms in the case of the chloride structure (cis and trans) were evaluated, as well as different multiplicities of spin and oxidation number of the metal (Co³⁺ and Co²⁺) were evaluated. considered. Different levels of calculation were used to obtain the Gibbs energy of the substitution reactions, in vacuum and in solvent (water, using the SMD model), namely: DFT/LANL2DZ/6-31G*, DFT/LANL2TZ/def2- TZVP and DFT/cc-pVTZ-DK, with DFT being the exchange-correlation functionals evaluated (B3LYP, BHandHLYP, Cam-B3LYP, TPSSh and M06-2X), with the aim of understanding thermodynamic aspects of a probable first reaction step. The results suggest that the first reaction step may involve coordination of the allyl compound with cobalt, since substitution reactions are favorable regardless of the nox or spin multiplicities of Co. CCSD(T) calculations are being performed to evaluate a adequate level of theory for the treatment of systems. The results obtained may assist in kinetic studies and proposition of a mechanism for allylation reactions catalyzed by Co.

COMMITTEE MEMBERS:
Presidente - ***.999.014-** - JULIANA ANGEIRAS BATISTA DA SILVA - UFPE
Interno - ***.451.424-** - JULIANO CARLO RUFINO DE FREITAS - UFCG
Externo ao Programa - 1753889 - EDUARDO DE CASTRO AGUIAR - UFRPEExterno à Instituição - RICARDO LUIZ LONGO - UFPE